1、be confident in sb/doing sth 对某人充满信心/做某事
2、be confident about dong sth/sth 对某事/某事充满信心
例句：
1、You must be confident in what you do.
你必须对所做的事有信心。
2、Carrick also appears to be confident in his ability.
卡里克也对他的能力很有信心。
3、In the long term, Americans can have reason to be confident in our economic strength.
长期地看，美国人应该有理由对我们的经济实力充满信心。
4、"We still have to be confident about next season," he added.
“我们对下赛季充满信心，”他说。
5、It is too soon to be confident about its hypotheses.
现在还不能确信其假设的真实性。
扩展资料
对比：
But people should be confident in whatever road they choose.
但是人们无论选择哪条路都要有信心。
But by relying on these principles, we can be confident in the future of our Nation and the world.
但是依据这些原则，我们对我们的国家和这个世界的未来依然有信心。
Only with this exercise would I be confident in diagnosing a WHO grade II diffuse infiltrating astrocytoma.
只有这样认真校对之后，才能考虑本例是否为WHO分类的弥漫性浸润性星形细胞瘤II级
Do you know that it is also possible to be confident about life?
那么面对生命你是否也有同样的自信呢？
Be confident about yourself and your clothes.
对自己及所穿的服装要有信心。
参考资料：百度百科：英语语法
I have confidence in my team to deliver a successful project.
She has confidence in her abilities to pass the exam.
He has confidence in the company's future prospects.